1. Field of the Invention
The invention relates to a pressing jaw for producing a non-detachable pipe joint having an upper jaw half and a lower jaw half, at least one rotation axis which pivotally mounts at least one jaw half, and a receiving region formed between the upper jaw half and the lower jaw half and having a receiving region axis, whereby the at least one jaw half is able to pivot between an open position and a closed position substantially transversely to the receiving region axis. The invention also relates to a fitting and to a system consisting of a pressing jaw according to the invention, wherein the fitting comprises a base body and a press sleeve. The invention further relates to a method for producing a non-detachable pipe joint using a pressing jaw and to a method for joining a fitting to a metallic pipe in a metallically sealing manner.
2. Description of Related Art
Pressing jaws, fittings, systems and methods of the type mentioned above are already known from the prior art, for example from the sectors of drinking water installation or heating installation. In this respect, a “non-detachable pipe joint” is understood in particular as meaning that the joint is not configured to be detached and reconnected, i.e. it can no longer be detached, or can only be detached with difficulty, in particular only by destroying the individual workpieces of the pipe joint.
It is intended that the pipe joint can be produced as simply and reliably as possible and will ensure a high degree of tightness for as long as possible. Pressing jaws or methods are preferably used to press workpieces such as fittings, pipes, sockets or the like substantially radially, i.e. transversely to the axis of the receiving region. In this respect, the receiving region axis extends approximately vertically to the area spanned between the jaw halves. In the case of a cylindrical receiving region, the axis of the receiving region substantially corresponds to the axis of the cylinder. When a workpiece is introduced into the receiving region, the receiving region axis and the workpiece axis of for example a pipe or fitting then substantially coincide, at least when the jaw halves are closed. The gripper-like closing movement of the jaw halves deforms two or more workpieces, for example a fitting and a pipe, which are arranged such that they at least partly overlap in the receiving region and as a result are joined together in a non-detachable manner.
For the closing movement of the pressing jaw, a pressing machine is often used, onto which the pressing jaw is fitted and which pushes a bolt or rollers between the rear ends of the jaw halves of the pressing jaw to close the front ends of the jaw halves forming the receiving region. As an alternative or in addition, for example a manual actuation of the pressing jaw can also be intended. The distinction into “upper” and “lower” (jaw half for example) should not be understood as being restrictive. In fact, the pressing jaw can be spatially arranged as required.
The prior art pressing procedures can, however, be disadvantageous. For example, the exertion of an all-round homogeneous pressing force on the workpieces to be pressed is made significantly more difficult using pressing jaws or methods provided for this purpose. Before the pressing procedure, pipes and fittings preferably have a rotationally-symmetrical and substantially round shape. However, after the pressing procedure, this symmetry can be disturbed due to pressing forces which act non-homogeneously on the juncture between pipe and fitting, which can impair the functionality of the joint in particular.
Furthermore, the materials, in particular plastics material or metal, of the workpieces which are stressed during the pressing procedure can exhibit inertia towards the pressing forces. This inertia, in the form of restoring forces, can mean that the material, deformed by the pressing procedure, strives to at least partly reproduce the initial state or the initial structure of the workpieces. This requires the user of a merely radially inwardly acting pressing method to increase the pressing forces to be exerted radially inwards for example, in order to obtain the desired pressing result. However, this represents a demand on the materials of the workpieces to be pressed which goes beyond the intended extent and thus is basically undesirable.
The previously mentioned problems can be resolved or at least reduced using a so-called axial pressing method in particular. Here, “axial” means that the workpieces to be pressed are moved at least partly along the workpiece axis or the receiving region axis. Although the restoring characteristics of the workpieces to be deformed also act in principle in the axial direction, the effects of an increased stress on the material due to the usually long axial extent of the workpieces compared to the radial extent can be minimised.
Pressing tools for an axial pressing of this type are, however, very large and bulky since they have to widely encompass the region to be axially pressed. For this reason, German published patent application DE 10 2008 010 083 A1, for example, discloses a method in which a pressing tool for radial pressing can also achieve an axial pressing along the receiving region axis by means of inclined pressing surfaces on the tool and on the fitting. A fitting can thus be pressed along the receiving region axis in spite of the movement of the jaw halves transversely to the receiving region axis.
However, to translate or deflect the pressing force, a particular path is required which is provided by the inclined surfaces on the outer peripheral surface of the fitting. In this respect, it is a problem that fittings are required which increase greatly in diameter, because the diameter of the fittings is increased due to the inclined pressing surfaces. On the one hand, this leads to larger and relatively unmanageable fittings and on the other hand, it also results in a greater consumption of material, i.e. in higher production costs of the fittings.
The previously described fittings which are to be pressed axially generally use a sealing element consisting of a flexible material, in particular an elastomer. Likewise, fittings having a seal between two metal workpieces, so-called metallically sealing fittings with axial pressing are known. Before pressing, these fittings to be axially pressed have radially inwardly projecting cutting edges or ribs which, during pressing, penetrate the material of the pipe to be joined and thereby produce the seal. Thus, the construction of the fittings is complex and costly to produce. Fittings of this type are known from U.S. Pat. No. 5,114,191, DE 100 26 083 C1 and DE 101 05 013 C1.
In addition, solder fittings of a very simple construction have been known for a long time. Solder fittings consist of a simple section of pipe, the internal diameter of which is generally the same as that of the section of pipe to be joined thereto. At least one end of the solder fitting is widened as a socket over a predetermined receiving portion to such an extent that the internal diameter substantially corresponds to the external diameter of the pipe to be joined. The pipe to be joined is then inserted into the widened portion, i.e. into the socket and the fitting and the section of pipe are joined in a material-uniting manner by solder.
For this reason, solder fittings enjoy a wide spectrum of use and are an economical alternative to press fittings due to their low production costs. Although they are considered to be metallically sealing due to the solder, solder fittings do not have a material purity because of the different metals of pipe and solder. Furthermore, the fittings have to be soldered on site in a laborious manner which, on the one hand is very time-consuming and on the other hand, subject to the surroundings, is not permitted. Thus, for diverse technical applications, no press fitting exists which is metallically-sealing, but nevertheless comparable in economic terms.